A larynx stroboscope is a device in which the flash discharge tube emits light by a trigger signal synchronous with a vocal cord vibration so that the vocal cords being vibrated can be observed as if they were at rest or moving at slow speed. The larynx stroboscope is most effective in diagnosing whether or not vocal cords are diseased or whether or not the motion of vocal cords is normal.
There has been a strong demand, in the field of modern diagnostic medicine, to provide a technique in which vocal cords are photographed while the vibration of the vocal cords is being observed. Such a photograph will provide a clear image of the vocal cords. However, in a conventional larynx stroboscope the observing light source and the photographing light source are provided separately. Hence, the operation of the conventional larynx stroboscope is rather difficult and not practical to use. Furthermore, with the conventional larynx stroboscope, when the observing flash light is used for photographing the vocal cords, the intensity of light thereof is generally inadequate, and accordingly it is necessary to carry out multiple exposure photography.
In general, the number of light emissions of the flash discharge tube effectuated while the shutter of a photographing camera is open depends on the number of vibrations of the vocal cords, and therefore it is necessary to change the exposure conditions of the camera in order to obtain a suitable exposure. In addition, if the synchronization of the vocal cords is changed even slightly, it is impossible to obtain a clear image of the vocal cords because of a multiple exposure resulting in a blurred image. Because of the above-described reasons, heretofore, it has been very difficult to obtain a clear image of vocal cords.